198 Miscellaneous, 



Thus no allusion was made to it four years afterwards by Max 

 Schultze, who, on the authority of F. Miiller, mentions the occur- 

 rence of one of Duges's species at Berlin. At the same time another 

 freshwater Nemertean, belonging to an undetermined species, was 

 reported from a peat-bog at Greifswald *. 



During this time a freshwater Nemertean was described by Leidy 

 in an incomplete fashion from the United States ; this animal was 

 found in the environs of Philadelphia, and was named Emea rubra f. 

 It was for the same worm that Diesing, in 1862, created the familj* 

 Emeida), without, however, having observed the animals which he 

 assigned to it J. 



Shortly before the appearance of Diesing's paper Prof. Schmarda 

 bad described, under the name Nemertes polylwpla, a new Nemer- 

 tean from the Lake of Nicaragua, which appears in all probability 

 to belong to a different type from that of all those with which we 

 have been dealing §. 



For some ten years from that time no naturalist seems to have met 

 with any freshwater Ncmerteans. In 1869 Czerniavsky, a Russian 

 zoologist, mentioned the existence of an entire fauna, and especially 

 Nemertoans, of a marine character in the fresh (or, at least, potable) 

 waters of Lake Paleostom, situated on the eastern shore of the 

 Black Sea ||. Shortly afterwards, in 1872, Fedtschenko published 

 an interesting study upon a Tctrastemma found by him in the neigh- 

 bourhood of Tashkend, in Turkestan, and which he called Tetra- 

 stemma turanicum. Fedtschenko, who was well acquainted with 

 the researches of his predecessors, unhappily, like Czerniavsky, wrote 

 his memoir in Russian, which has led to its being neglected by 

 almost every one, although it is accompanied by a plate ^. 



After this, the first paper in which we once more find mention 

 of a freshwater Nemertean appeared in 1884 **. In the article in 

 question W. A. Silliman deals (under the name Tetrastemma aquarum 

 dulciaiii) with a worm which is of universal distribution, although 

 always in small numbers, in the county of Monroe (New York 



* ' J3eitrage zm* Naturgescliichte der Turbellarien,' 1851. 



t Proc. Acad, Nat. Sci. Philadelphia, vol. v., Dec. 1850 and Oct. LS.jl. 



I Sitzinigsber. k.-k. Akad. Wiss. Wien, math.-naturw. CI., Bd. xlv. 

 (18(32). 



§ ' Neiie Turbellarien, Rotatorieu,' &c., Ed. i. Heft i. (1859). The 

 great lake of Nicaragua (Cocibolco), whose waters, which are entirely 

 sweet, embrace an area of more than 3476 square miles ('' plus de 9000 

 kilometres carres"), contains a very interesting fauna. Among other 

 fishes Plagiostomes of a characteristic marine facies are found in it, espe- 

 cially species of Pristis, or saw-fish. 



II Czerniavsky's paper was published at Moscow in a pamphlet of such 

 limited circulation that it has even escaped the notice of Fedtschenko 

 and von Kennel ; I am acquainted with it only thi'ough a statement by 

 Leuckart ("]?erieht fiber wiss. Leistuugen in den Jahren 1868 und 1869," 

 Arch. f. Natm-geschichte, 33 Jahrg. 1869, Bd. ii. p. 212). The study of 

 the fauna of Lake Paleostom, which was separated from the Black Sea at 

 a recent epoch, would furnish arguments analogous to those which 

 result from the papers of von Kennel, which are mentioned below. 



^ ' Proces-verb. Soc. imp. amis Sc. nat. Antnrop. et Ethnogr. Univer- 

 site de Mo&cou,' vol. x. 



** Zeitschr. f. wiss, Zool. IW, xli. Heft 1, 



